JP2016057160A - Method of simultaneously measuring flow velocity and object displacement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of simultaneously measuring the displacement of an object in a fluid and the velocity of the fluid.SOLUTION: A measurement particle 40 is input into the flow of water, and the water and a side surface 11 of an underwater columnar object 10 that is in contact with the water is irradiated with slit light 14 tilted with respect to the normal direction of the side surface 11. Then, the time variation of stripes appearing on the surface of the underwater columnar object 10 due to the irradiation of the slit light 14 is shot by a high-speed camera 2 having an optical axis 16 tilted with respect to the incident direction of the slit light 14. On the basis of the shooting, the displacement of the columnar object is measured. By shooting, with the high-speed camera 2, the time variation of the slit light 14 scattered by the underwater measurement particle 40, the velocity of the water is measured.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for measuring the flow velocity of a fluid and the displacement (movement) of the object at a time in a system in which at least a part of the object is in contact with the fluid.

  Conventionally, as a method for measuring the flow velocity of a fluid, there is one described in JP-T-2010-503832 (Patent Document 1). In this method of measuring the flow rate of fluid, tracer particles are flowed into the fluid, and then a specific region of the fluid is continuously photographed with time by a camera. Then, the flow of the fluid carrying the tracer particles is analyzed by measuring the moving direction and speed of the tracer particles based on the temporally different images taken by the camera.

Special table 2010-503832 gazette

  However, the inventor of the present application has found that there is a possibility that the fluid flow cannot be accurately analyzed in the system to be measured by the above method.

  That is, when an object is arranged in the fluid, turbulent flow such as Karman vortex is generated downstream of the object. When the object can be displaced by the force from the fluid, the object vibrates (displaces) due to the turbulent flow.

  Here, when the object vibrates, the flow of the fluid fluctuates due to a pressure difference generated in the fluid based on the vibration of the object. Then, the vibration of the object is further influenced by the fluctuation of the fluid flow.

  Therefore, since the vibration of the object and the flow of the fluid interact in a complicated manner, when the object exists in the fluid, the vibration of the object and the velocity of the fluid are necessary to accurately analyze the flow of the fluid. It is indispensable to measure together in time series.

  However, the conventional measurement method cannot measure the vibration of the object and may not be able to accurately analyze the fluid flow.

  Accordingly, an object of the present invention is to provide a method capable of measuring the displacement of an object in a fluid and the velocity of the fluid at a time.

In order to solve the above problems, the method of measuring the flow velocity and the object displacement of the present invention at one time is as follows:
A particle mixing step for mixing measurement particles into the fluid flow;
A slit light irradiation step of irradiating the fluid and at least a part of the slit light inclined with respect to the normal direction of at least a part of the fluid contact part of the fluid in contact with the fluid;
An imaging device in which the optical axis is tilted with respect to the incident direction of the slit light, and the displacement of the object is determined based on photographing the temporal variation of the stripes appearing on the surface of the object by the irradiation of the slit light. A displacement measuring step to be measured;
And a flow velocity measuring step for measuring a flow velocity of the fluid based on photographing the temporal variation of the slit light scattered by the measurement particles in the fluid with the imaging device.

  In addition, irradiating the said slit light to said at least one part means irradiating a slit light to the area | region containing the said at least one part.

  According to the present invention, since the slit light tilted with respect to the normal direction of at least a part of the fluid contact part is irradiated on the at least part, a light stripe can be generated on the surface of the object by the slit light, The position where the stripes of light appear on the object can be measured for each time by the light cutting method. Accordingly, the temporal variation of the movement of the object (vibration of the object) can be measured by the light cutting method by photographing the temporal variation of the light stripe appearing on the surface of the object with the imaging device. Further, according to the present invention, the measurement particles in the slit light can be brightly illuminated by the scattering of the slit light by the measurement particles. Then, by imaging the temporal transition of measurement particles with an imaging device, PIV (Particle Image Velocimetry) and PTV (Particle Tracking Velocimetry) can be used, and the velocity of the fluid can be measured. Therefore, since both the fluid velocity and the displacement of the object can be measured, the state of the fluid flow can be analyzed accurately.

  In addition, according to the present invention, since slit light (thin sheet-like light) is used, not only can the behavior of the measurement particles in a two-dimensional plane be accurately detected using PIV or PTV, but also slit light was used. The optical cutting method can also be performed, and the fluctuation of the object can be accurately measured by the optical cutting method. Therefore, compared to the case where a new sensor for detecting the movement of the object is separately installed and a double system is adopted to additionally track the fluctuation of the object (vibration of the object), It is possible to make a remarkably simple single system, and it is possible to measure the velocity of the fluid and the displacement of the object remarkably easily and inexpensively.

In one embodiment,
A plurality of the flow velocity measurement steps are performed in a state where at least one of the incident direction and the optical axis is different.

  According to the above embodiment, when a plurality of flow velocity measurement steps are performed in a state where the incident directions of the slit light are different from each other, a plurality of different two-dimensional regions in the fluid flow area can be illuminated with the slit light. Further, when a plurality of flow velocity measurement steps are performed in a state where the optical axes are different from each other, it is possible to perform imaging of regions different from each other. Therefore, the three-dimensional velocity of the measurement particle can be measured, and the three-dimensional velocity of the fluid can be measured.

In one embodiment,
The displacement measuring step is performed using a plurality of different slit lights.

  In addition, a plurality of displacement measurement steps may be performed, and slit light may be incident from one incident direction in each displacement measurement step. In the displacement measurement step, a plurality of slit lights may be emitted simultaneously from a plurality of different incident directions. You may do it.

  According to the above-described embodiment, the slit light different from each other is irradiated onto the object, so that the slit light can be irradiated onto a plurality of different places on the object. Therefore, not only the parallel movement of the object but also the rotational movement (twist) of the object can be measured, and the state of fluctuation (vibration) of the object can be analyzed in more detail.

  According to the method of the present invention, the displacement of an object in a fluid and the flow velocity of the fluid can be measured at a time, and the fluid flow can be analyzed accurately. Further, according to the method of the present invention, it is possible to measure the flow velocity of the fluid and the displacement of the object at once with a much simpler system.

It is a schematic block diagram of the system which can implement | achieve the method of measuring the flow velocity and object displacement of one Embodiment of this invention at once. It is a figure explaining the measurement principle of PIV. It is a figure which shows a 1st small window and the function f (x, y). It is a figure which shows a 2nd small window and the function g (x, y). It is a figure which shows an example of a correlation plane. It is a figure showing the moving direction and magnitude | size of particle | grains in a 1st small window. It is a schematic diagram explaining the principle of the optical cutting method in case a slit light source has a light projection lens.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a system capable of realizing a method for measuring a flow velocity and an object displacement at one time according to an embodiment of the present invention. FIG. 1 is a cross-sectional view showing a two-dimensional plane. Further, in the explanation using FIG. 1, the principle of the method is mainly explained, the measurement target is a simple system, and how the velocity (direction and size) of the fluid and the fluctuation (vibration) of the object are determined. Explain how to measure.

  As shown in FIG. 1, this system includes a slit light source 1 and a high-speed camera 2 as an imaging device. The slit light source 1 emits slit light 14 that is thin sheet-like light. The slit light source 1 generates slit light 14 with a laser light source and a cylindrical lens. On the other hand, the speed camera 2 is capable of photographing 10,000 or more frames per second. The velocity camera 2 includes a light receiving lens and a two-dimensional detector composed of a PSD (photo-sensitive detector) or the like.

  On the other hand, the system to be measured has flow walls 30 and 31 that define the flow of water as an example of the fluid, and the water flows in the direction of arrow A. Each said wall surface 30 and 31 is extended in the direction substantially parallel to the direction of the flow of water. As shown in FIG. 1, this measurement system has a columnar object 10 as an example of an object, and the columnar object 10 exists in the flow of water. As shown in FIG. 1, the columnar object 10 has a planar side surface 11 extending in a direction substantially parallel to the direction of water flow.

  In FIG. 1, the emission direction of the slit light 14 emitted from the slit light source 1 (corresponding to the incident direction of the slit light 14) is θ (0 ° <θ <90 °: normal direction B of the side surface 11: The closer θ is to 90 °, the closer the traveling direction of the slit light 14 is to a direction parallel to the flow of water). The angle θ may satisfy 0 ° <θ <90 °, but as θ, for example, an angle of 40 ° to 50 ° including 45 ° can be suitably employed.

  As shown in FIG. 1, the optical axis 16 of the high-speed camera 2 is substantially orthogonal to the emission direction of the slit light 14. Each of the emission direction of the slit light 14 and the extending direction of the optical axis 16 is located on the same plane shown in FIG. 1, and the side surface 11 extends in a direction substantially perpendicular to the plane shown in FIG. ing. In FIG. 1, straight lines 50 and 51 indicate ranges that can be captured by the high-speed camera 2.

  In the above configuration, in the method of this embodiment, the speed of water and the fluctuation of the columnar object are measured as follows.

  First, a particle mixing step is performed. In this particle mixing step, a plurality of measurement particles (tracer particles) 40 are mixed in the water flow. Here, each measurement particle is a nylon particle having a diameter of several tens of micrometers, and the density of each nylon particle is substantially the same as that of water.

  Subsequently, a slit light irradiation step is performed. In this slit light irradiation step, slit light 14 is emitted from the slit light source 1 of the system. Specifically, the slit light 14 tilted with respect to the normal direction of the side surface 11 constituting at least a part of the water contact portion is irradiated onto the water and the side surface 11.

  Next, a flow velocity measurement step is performed. In this flow velocity measurement step, the temporal variation of the slit light 14 scattered by the measurement particles 40 in the water is photographed in time series by the high-speed camera 2, and also based on the PIV using the slit light 14. To measure the flow of water.

  FIG. 2 is a diagram for explaining the measurement principle of PIV.

  In this flow velocity measurement step, referring to FIG. 2, a part of the two-dimensional area 48 illuminated by the slit light 14 is continuously photographed by the high-speed camera 2.

Then, a first small window (area) 46 is set in the image at the first time. Thereafter, the shift range from the first small window when searching for the destination is set in the image at the second time after Δt [s] time from the first time. Then, the shift within the shift range is performed to search for the transition destination of the first small window. Specifically, first, the small window at the second time is finely shifted from the first small window vertically and horizontally in increments of 1 pixel (in some cases in increments of 1 pixel or less). Then, for each second small window (region), the cross-correlation function R _fg (x, y, α, β) is expressed by the following equations (1) to (3) between the images of the first and second small windows. The second small window having the largest cross-correlation function with respect to the first small window is specified. Then, a movement (speed) vector is obtained from the positional relationship between the first small window and the second small window having the largest cross-correlation function with respect to the first small window. This is performed for all the first small windows in the measurement range, and a map of the movement vector is formed.

ここで、ｉ,ｊ,α,βは、整数であって、ピクセルを特定する指数であり、α,βを変えることによって、シフト先の画像を特定する。また、ｎ,ｍは、小窓領域ｎ×ｍ（ピクセル）を確定する整数であり、関数ｆ（ｘ,ｙ）と関数ｇ（ｘ,ｙ）の夫々は、座標ｘ,ｙでの輝度を表す関数である。また、関数ｆ（ｘ,ｙ）は、時刻ｔの画像を基に定義され、関数ｇ（ｘ,ｙ）は、時刻（ｔ＋Δｔ［ｓ］）の画像を基に定義される。また、ｘ,ｙは、２次元平面での変数であり、ｘ,ｙを確定すると、第１小窓を特定できる。尚、小窓領域は、例えば、３０×３０（ピクセル）とか、４０×４０（ピクセル）を使用できるが、小窓領域ｎ×ｍ（ピクセル）は、これに限らず、如何なる大きさの領域で定義されても良い。

Here, i, j, α, and β are integers and are indices for specifying pixels, and the image to be shifted is specified by changing α and β. N and m are integers that define the small window region n × m (pixel), and the function f (x, y) and the function g (x, y) respectively indicate the luminance at the coordinates x and y. It is a function to represent. The function f (x, y) is defined based on the image at time t, and the function g (x, y) is defined based on the image at time (t + Δt [s]). Further, x and y are variables on a two-dimensional plane, and when x and y are determined, the first small window can be specified. For example, 30 × 30 (pixels) or 40 × 40 (pixels) can be used as the small window region. However, the small window region n × m (pixel) is not limited to this, and any size region can be used. May be defined.

FIG. 3 is a diagram illustrating the first small window and the function f (x, y), and FIG. 4 is a diagram illustrating the second small window and the function g (x, y). As shown in FIGS. 3 and 4, α and β are measures of the shift amount. R _fg (x, y, α, β) is calculated by changing each α, β, and a correlation plane shown in FIG. 5 as an example is calculated. The correlation plane is a plane in which x and y are fixed and variables are represented by α and β that define the direction and magnitude of the shift. Then, based on α and β having the maximum values in the correlation plane, the second small window most correlated with the first small window is specified, and as shown in FIG. 6, the movement of particles in the first small window Calculate direction and size.

  In summary, in the flow velocity measurement step, a small window image centered on the measurement point is cut out from two time-difference imaged particle images. Then, using the cross-correlation function, the positional relationship between two small windows having a time difference that maximizes the similarity between the images is determined. And from the positional relationship of these small windows, the average moving amount (water flow speed) of particles in each small window is measured.

  Further, the displacement measurement step is performed simultaneously with the flow velocity measurement step. In this displacement measurement step, the high-speed camera 2 measures the displacement of the columnar object 10 by photographing temporal fluctuations of stripes appearing on the surface of the columnar object 10 based on the slit light 14.

  Specifically, with reference to FIG. 1, it is assumed that the columnar object 10 periodically vibrates between a position indicated by a dotted line 60 and a position indicated by a solid line 61 in FIG. In this case, when the columnar object 10 is present at the position of the dotted line 60, the stripe of the slit light 14 is present at the position indicated by C in FIG. When it exists in the position of the continuous line 61, the stripe of the slit light 14 exists in the position shown by D in FIG.

  Therefore, the position of the slit light source 1 and the position of the high-speed camera 2 are known, the distance between the photodetector and the light receiving lens in the high-speed camera 2 is also known, and the image captured by the high-speed camera 2 is captured. Since the pixel size is also known, the position of C and the position of D can be specified by the principle of triangulation, and the moving range of the columnar object 10 can be measured. Further, since the time difference between two consecutive images taken by the high-speed camera 2 is known, the number of frames taken by the high-speed camera 2 before the columnar object 10 moves from the dotted line 60 to the solid line 61. By counting, the time elapsed until the columnar object 10 moves from the dotted line 60 to the solid line 61 can be calculated. Therefore, the frequency of the columnar object 10 can also be measured. In this case, it is assumed that the columnar object 10 vibrates after the side surface 11 of the columnar object 10 is maintained perpendicular to the paper surface of FIG. However, such a condition is not always necessary, and the position of the object illuminated by the slit light is determined by the light cutting method based on the stripes on the captured image based on the slit light, as described in FIG. 7 below. It can be identified and the movement of the object can be measured.

  FIG. 7 is a schematic diagram for explaining the principle of the light cutting method when the slit light source has a light projection lens.

In FIG. 7, since the distance d between the detector and the light receiving lens is known, the azimuth angle of the light axis P ₀ a ₀ (or P ₁ a ₁ ) is calculated, and the distance to the object plane is calculated based on the principle of triangulation. L is determined. The light cutting method measures the distance to an object based on basically the same principle as a distance sensor. The principle is the same as measuring the surface shape by moving the distance sensor along the object surface. In this way, based on the stripes of the captured image, it is possible to specify the position of the portion irradiated with the slit light in the object (not limited to the columnar object).

  In addition, the method of the said embodiment can be expressed as follows. That is, after a columnar object 10 having two side surfaces facing each other in the flow direction is set up in the flow of water mixed with the measurement particles 40, a predetermined angle is formed on one side surface 11 of the two side surfaces. Then, the slit light 14 is irradiated. Then, based on two images taken continuously during a minute time Δt [s] by a single high-speed camera (image sensor) 2 arranged in a direction that is tolerance (orthogonal) to the irradiation light, the measurement particle 40 The speed of water is obtained from the displacement of. At the same time, the three-dimensional position information and the posture information of the columnar object 10 are obtained from the two images, and the vibration (movement) of the columnar object 10 is obtained from these information.

  According to the above-described embodiment, the slit light 14 tilted with respect to the normal direction of the side surface 11 of the columnar object 10 is irradiated to the side surface 11, so that a light stripe can be generated on the surface of the columnar object 10 by the slit light 14. Thus, the position where the stripes of light appear in the columnar object 10 can be measured for each time by the light cutting method. Therefore, the temporal variation of the movement of the columnar object 10 (vibration of the columnar object 10) is observed by the light cutting method by photographing the temporal variation of the light stripe appearing on the surface of the columnar object 10 with the high-speed camera 2. It can be measured. Moreover, according to the said embodiment, the measurement particle | grains 40 in the slit light 14 can be made to shine brightly by scattering of the slit light 14 by the measurement particle | grains 40. FIG. Then, by photographing the temporal transition of the measurement particles 40 with the high speed camera 2, the speed of water can be measured with the PIV. Therefore, since both the speed of water and the displacement of the columnar object 10 can be measured, the state of water flow can be analyzed accurately.

  In addition, according to the above embodiment, since the slit light 14 is used, not only can the behavior of the measurement particle in a two-dimensional plane be accurately detected using PIV, but also a light cutting method using the slit light 14 can be performed. Thus, the fluctuation of the columnar object 10 can also be accurately measured by the light cutting method. Therefore, a new sensor that detects the movement of the columnar object is installed separately, and the system is compared with the case of adopting a dual system and additionally tracking object fluctuation (object vibration). It is possible to make a remarkably simple single system, and the water speed and the displacement of the columnar object 10 can be measured remarkably simply and inexpensively.

  In addition, according to the above-described embodiment, since the emission direction of the slit light 14 and the extending direction of the optical axis 16 are substantially orthogonal, when the high-speed camera 2 captures the slit light 14, the focus is adjusted. It is easy to match and more accurate measurement can be performed. If the exit direction of the slit light and the extending direction of the optical axis are not substantially orthogonal, the difference in distance between the region close to the high-speed camera 2 and the region far from the high-speed camera 2 in the same image becomes large. In some cases, it is necessary to perform correction in the depth direction, and measurement cannot be performed easily and quickly.

  In the above embodiment, the slit light source 1 generates the slit light 14 with the laser light source and the cylindrical lens. However, in the present invention, the slit light source may generate slit light using white light and a slit mask, or may generate slit light using a laser light source and a polygon mirror. In the present invention, the slit light source may generate slit light using a line LED and a projection lens, or may generate slit light by any other method.

  Further, in the above embodiment, the high-speed camera 2 was able to capture 10,000 thousands of frames per second, but in the present invention, by replacing the imaging device depending on the measurement target, The number of frames that can be shot may be changed freely, and the number of frames that can be shot per second may be larger or smaller than ten thousand frames.

  In the above embodiment, the fluid is water, and the measurement particles 40 are nylon particles having a diameter of several tens of micrometers. However, in the present invention, the fluid may be any liquid other than water. Further, the diameter of the measurement particle can be freely changed depending on the measurement object, and the diameter may be any value other than several tens of micrometers. Also, the density of the measurement particles can be freely changed according to the specification, and the density of the measurement particles may be the same as the density of the water to which it flows or may be different from the density of the water to which it flows. The material of each measurement particle is not limited to nylon, and any other resin material may be used, or a material other than resin. Further, each measurement particle may be an oil drop or a bubble present in water. In the present invention, the fluid may be a gas such as air. In that case, for example, smoke particles may be used as measurement particles.

In the above embodiment, the flow velocity measurement step is performed by PIV using the cross-correlation function R _fg (x, y, α, β). However, in the present invention, the flow velocity measurement step is performed using the Fourier transform cross-correlation method. It may be performed by the used PIV (using fast Fourier transform (FFT)) or by the autocorrelation method PIV (Auto-correlation PIV). Moreover, the flow velocity measurement step may be performed by two-dimensional PIV (Optical Flow PIV) using optical flow, and two-way DP matching ((Dynamic Programming Matching): Matching that allows local small deformation of signal waveform) ) May be used.

  In the above embodiment, PIV is used to analyze the velocity (direction and size) of the fluid. In the present invention, PTV is used to analyze the velocity (direction and size) of the fluid. You may do it. In addition, when using PTV, since the locus | trajectory of each measurement particle | grain will be searched, it is preferable to employ | adopt the particle | grain which does not change a magnitude | size with time as a measurement particle | grain.

  In the above embodiment, the exit direction of the slit light 14 and the optical axis 16 of the high-speed camera 2 are substantially orthogonal. However, in the present invention, the exit direction of the slit light and the optical axis of the photographing apparatus are The extending direction may intersect at any angle other than substantially orthogonal.

  Moreover, in the said embodiment, although the object was the columnar object 10, in this invention, an object may have what kind of three-dimensional shape.

  Moreover, in the said embodiment, the flow velocity measurement step and the displacement measurement step were performed at the same time (the flow velocity measurement step and the displacement measurement step were performed in a state where there was a time during which they were performed simultaneously). However, in the present invention, the displacement measurement step may be performed after the flow velocity measurement step, or the flow velocity measurement step may be performed after the displacement measurement step.

Moreover, in the said embodiment, the said flow velocity measurement step was performed with time in one pattern which fixed the emission direction of the slit light 14, and the optical axis of the high-speed camera 2. FIG. However, in the present invention, the flow velocity measurement step may be performed with a plurality of patterns in which at least one of the emission direction of the slit light and the optical axis is different from each other. According to this modification, the flow velocity measurement step can be performed a plurality of times in a state where the incident directions of the slit light are different from each other, and a plurality of different two-dimensional regions in the fluid flow area are illuminated with the slit light. Can do. Moreover, the flow velocity measurement step can be performed a plurality of times in a state where the optical axes are different from each other, and imaging of different areas can be performed. Therefore, the movement of the measurement particles at each point in the three-dimensional space can be easily analyzed, and the three-dimensional velocity of the fluid can be easily measured. Further, the cross-correlation function R _fg (x, y, z, α) is obtained by performing the flow velocity measurement step by simultaneously emitting a plurality of slit lights or performing the flow velocity measurement step using a plurality of imaging devices. , β) can be calculated by a function f (x, y, z) defined by three-dimensional coordinates and g (x, y, z). In this case, each point in the three-dimensional space of the measurement particle It is possible to measure and analyze the movement of the car in more detail.

  Moreover, in the said embodiment, the said displacement measurement step was performed fixing the emission direction of the slit light 14. FIG. However, in the present invention, the displacement measuring step may be performed using a plurality of slit lights. In this way, since a plurality of slit lights can be irradiated to different locations in the object, not only the parallel movement of the object but also the rotational movement (twisting of the object) can be obtained. If the object is rotationally moved and the slit light emission direction is fixed at one, the rotational movement of the object cannot be detected when the slit light is applied to the rotational axis of the object. On the other hand, when a plurality of slit lights are irradiated to different locations in the object, the slit light is always irradiated to the location of the object that rotates by the rotational motion, so by measuring the displacement of the plurality of slit lights, The rotational movement of the object can also be measured.

  In this case, it is preferable to perform a plurality of displacement measurement steps and use only one slit light in each displacement step, rather than using two slit lights at the same time. This is because it is preferable to extract only a flow of a certain cross section by the slit light source, and it is preferable that light does not enter the particle from many directions.

  For example, the method of the present invention can be applied to a lubricant in a rolling bearing in which a rolling element (object) is disposed between an inner ring and an outer ring (when a cage is used, the cage and the rolling element constitute an object) ( It can be preferably used to measure the velocity of the fluid), and can be suitably used to measure the vibration excitation phenomenon caused by the flow of air (fluid) passing through the wing (object) of the aircraft.

  Further, the method of the present invention can be suitably used for analysis of fluid flow in various parts of an automobile. This is because in recent years, various parts of automobiles have become more compact and smaller, but in order to compensate for the reduction in output accompanying this, the rotational speed of the motor has become higher and fluid This is because the speed of is also faster. In addition, the method of the present invention can be used suitably not only when the fluid velocity is high but also when the material of the object is light, such as resin, and is more suitable when the thickness of the object of the light material is thin. Can be used for

  However, the method of the present invention may be used for measuring the velocity of the fluid and measuring the fluctuation of the object in any apparatus as long as the apparatus has a displaceable object disposed in the fluid flow. In addition, it is needless to say that a new embodiment can be constructed by combining two or more configurations among all the configurations described in the above-described embodiments and modifications.

DESCRIPTION OF SYMBOLS 1 Slit light source 2 High speed camera 10 Columnar object 11 Side surface of columnar object 14 Slit light 16 Optical axis 40 Measurement particle 46 1st small window

Claims (3)

A particle mixing step for mixing measurement particles into the fluid flow;
A slit light irradiation step of irradiating the fluid and at least a part of the slit light inclined with respect to the normal direction of at least a part of the fluid contact part of the fluid in contact with the fluid;
An imaging device in which the optical axis is tilted with respect to the incident direction of the slit light, and the displacement of the object is determined based on photographing the temporal variation of the stripes appearing on the surface of the object by the irradiation of the slit light. A displacement measuring step to be measured;
A flow velocity measuring step for measuring a flow velocity of the fluid based on photographing the temporal variation of the slit light scattered by the measurement particles in the fluid with the imaging device. And measuring object displacement at once. The method for measuring the flow velocity and the object displacement according to claim 1 at a time,
A method of measuring a flow velocity and an object displacement at a time, wherein a plurality of the flow velocity measurement steps are performed in a state where at least one of the incident direction and the optical axis is different. The method for measuring the flow velocity and the object displacement according to claim 1 or 2 at a time,
A method for measuring a flow velocity and an object displacement at a time, wherein the displacement measuring step is performed using a plurality of different slit lights.

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